Solve.
-The number of miles per gallon of gasoline that a car averages varies inversely as the average speed the car travels. A car gets 20 miles per gallon at 60 mph. How many miles per gallon will it get at 66 mph?
A)22 miles per gallon
B)0.05 miles per gallon
C)18.2 miles per gallon
D)0.06 miles per gallon

Question

Quizplus · Accepted Answer

The relationship between miles per gallon (mpg) and speed is inversely proportional, meaning as one increases, the other decreases. The formula for inverse variation is $y = \frac{k}{x}$, where $k$ is the constant of variation. From the given information, when the car travels at 60 mph, it gets 20 mpg. We can use this to find $k$: $20 = \frac{k}{60}$, so $k = 20 \times 60 = 1200$. To find the mpg at 66 mph, we use the constant $k$ and solve for $y$: $y = \frac{1200}{66} = 18.18$, which rounds to 18.2 miles per gallon.

Solve. -The Number of Miles Per Gallon of Gasoline That a a Car